1. Field of the Invention
The present invention relates to a throttle structure for allowing a fluid to flow therethrough, and a flow meter incorporated with the throttle structure, for measuring a flow rate of a fluid passing through a fluid passage by the aid of the incorporated throttle structure.
2. Description of the Related Art
A flow meter for measuring the flow rate of a fluid passing through a fluid passage is generally used, which is represented by a flow meter incorporated therein with a throttle structure for allowing the fluid to pass therethrough, for example, an orifice 1 made of stainless steel as shown in FIG. 17. The orifice 1 has a minute hole 2 which is formed as a fluid passage having a diameter of 10 xcexcm to 20 xcexcm. The minute flow rate of the fluid passing through the fluid passage connected with the flow meter can be measured, for example, by detecting the temperatures and the pressures on the inflow side and on the outflow side of the orifice 1.
However, when the minute hole 2 of 10 xcexcm to 20 xcexcm is formed for the conventionally used orifice 1 by means of machining, it is necessary to perform complicated working steps. Further, an inconvenience arises such that the dimensional error of the hole 2 is increased. Furthermore, a difficult problem arises such that the production cost is expensive. For example, the failure of correct measurement of the flow rate of a fluid or a process fluid to be used for an apparatus for producing semiconductor parts causes a factor to produce defective parts, which makes it extremely difficult to produce products required to have strict qualities.
A general object of the present invention is to provide a throttle structure which makes it possible to conveniently machine a fluid passage for allowing a fluid to pass therethrough and which makes it possible to prevent the occurrence of the dimensional error of the fluid passage as less as possible.
A principal object of the present invention is to provide a flow meter incorporated with a throttle structure which makes it possible to correctly measure the flow rate of a fluid passing through the throttle structure.
Another object of the present invention is to provide a throttle structure and a flow meter incorporated with the throttle structure which make it possible to achieve the inexpensive production cost of the throttle structure and the flow meter incorporated with the throttle structure.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.